Recycling method of fluorgypsum

Abstract

The invention provides a fluorgypsum recovery method which comprises the following steps: mixing fluorgypsum and lime according to a set proportion, and grinding in a ball mill to obtain gypsum powder with a preset particle size; mixing and stirring the gypsum powder and an ammonium chloride solution according to a preset proportion to obtain a mixed solution, and filtering the mixed solution to obtain a filter cake; placing the obtained filter cake in an ammonia water solution for stirring, adding a carbon source in a stirring state, adjusting the sulfur-carbon ratio and the ammonia-carbon ratio in the mixed solution to a preset ratio, and then reacting for a preset time; after the reaction is finished, filtering, collecting filtrate, and sequentially carrying out evaporation concentration, cooling crystallization and centrifugal separation to obtain an ammonium sulfate crystal finished product; and adding a potassium chloride solid into the residual filtrate, carrying out a preset reaction, cooling to normal temperature, crystallizing, and centrifugally separating to obtain a potassium sulfate crystal finished product. The problem that the conversion efficiency is not high when fluorgypsum is recycled in the prior art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of fluorgypsum recovery, and in particular to a fluorgypsum recovery method. Background Art

[0002] Fluorogypsum mainly comes from the waste residue generated during the preparation of hydrofluoric acid. Its main component is anhydrous calcium sulfate (CaSO4), with a content of up to 95%. The newly discharged fluorogypsum contains excessive amounts of HF, H2S04, etc. It is a highly corrosive, toxic and harmful waste. It also has a slow hydration rate and lacks early strength. It cannot be directly used as a cementitious material in the construction industry, but can only be used as a retarder in cement production.

[0003] In the prior art, dihydrate gypsum is generally obtained by hydrating anhydrous gypsum, and then the dihydrate gypsum is recycled accordingly. However, since it is difficult for newly discharged fluorinated gypsum to hydrate into dihydrate gypsum under normal conditions, most companies currently use the method of long-term storage in slag yards to allow it to hydrate naturally, and then use it after forming dihydrate gypsum. This results in low conversion efficiency of fluorinated gypsum recycling. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a method for recovering fluorinated gypsum, aiming to solve the problem of low conversion efficiency when recovering fluorinated gypsum in the prior art.

[0005] The embodiment of the present invention is implemented as follows:

[0006] A method for recovering fluorgypsum, comprising:

[0007] Mixing fluorinated gypsum and lime in a set ratio, and then grinding them in a ball mill to obtain gypsum powder with a preset particle size;

[0008] The gypsum powder and the ammonium chloride solution are mixed and stirred in a preset ratio to obtain a mixed solution, and the mixed solution is filtered to obtain a filter cake;

[0009] The obtained filter cake is placed in an ammonia solution and stirred, a carbon source is added under stirring, and the sulfur-carbon ratio and ammonia-carbon ratio in the mixed solution are adjusted to preset ratios and reacted for a preset time;

[0010] After the reaction is completed, the reaction is filtered, and the filtrate is collected and evaporated, concentrated, cooled, crystallized, and centrifuged to obtain the finished ammonium sulfate crystals;

[0011] Potassium chloride solid is added to the remaining filtrate, and after a preset reaction, it is cooled to room temperature for crystallization and centrifuged to obtain a finished potassium sulfate crystal product.

[0012] Furthermore, in the above-mentioned method for recovering fluorinated gypsum, the particle size of the gypsum powder is less than 100-150 meshes.

[0013] Furthermore, in the above-mentioned method for recovering fluorinated gypsum, the mass fraction of the ammonium chloride solution is 5-10%, and the gypsum powder and the ammonium chloride solution are mixed in a mass ratio of 1:3-5.

[0014] Furthermore, in the above-mentioned method for recovering fluorinated gypsum, the stirring speed of the gypsum powder and the ammonium chloride solution is 60 to 120 r / min, and the stirring time is 3 to 6 hours.

[0015] Furthermore, in the above-mentioned method for recovering fluorinated gypsum, the carbon source includes ammonium carbonate or carbon dioxide.

[0016] Furthermore, in the above-mentioned method for recovering fluorinated gypsum, the sulfur-carbon ratio is 1.05-1.2, the ammonia-carbon ratio is 2.0-2.2, and the reaction time is 1-1.5 hours.

[0017] Furthermore, in the above-mentioned method for recovering fluorinated gypsum, in the steps of adding potassium chloride solid to the filtrate, carrying out a preset reaction, cooling to room temperature for crystallization, and centrifuging to obtain a finished potassium sulfate crystal product, the nitrogen-potassium ratio is 1 to 1.10.

[0018] Furthermore, in the above-mentioned fluorine gypsum recovery method, the preset reaction is to heat up to 85-95° C. under stirring and keep the reaction warm for 1-1.5 hours.

[0019] Furthermore, the above-mentioned method for recovering fluorinated gypsum, wherein before the step of collecting the filtrate and sequentially performing evaporation concentration, cooling crystallization and centrifugal separation to obtain the finished ammonium sulfate crystals, further comprises:

[0020] The filter cake is collected and used for neutralization with the fluorgypsum.

[0021] Furthermore, the above-mentioned method for recovering fluorinated gypsum, wherein the steps of adding potassium chloride solid to the remaining filtrate, performing a preset reaction, cooling to room temperature for crystallization, and centrifuging to obtain a finished potassium sulfate crystal product further include:

[0022] The filtrate from which the potassium sulfate crystal product is recovered is evaporated and concentrated, cooled and crystallized, and then centrifuged to obtain ammonium chloride solid for mixing with the gypsum powder.

[0023] The invention comprises the following steps: mixing fluorinated gypsum and lime in a set ratio, and then grinding the mixture in a ball mill to obtain gypsum powder with a preset particle size; mixing the gypsum powder and ammonium chloride solution in a preset ratio to obtain a mixed solution, and filtering the mixed solution to obtain a filter cake; placing the obtained filter cake in an ammonia solution for stirring, adding a carbon source under stirring, adjusting the sulfur-carbon ratio and the ammonia-carbon ratio in the mixed solution to preset ratios, and then reacting for a preset time; filtering after the reaction is completed, collecting the filtrate, and sequentially performing evaporation concentration, cooling crystallization, and centrifugal separation to obtain a finished ammonium sulfate crystal product; adding potassium chloride to the remaining filtrate; Solid, after the preset reaction, is cooled to room temperature for crystallization and centrifugal separation to obtain the finished potassium sulfate crystals. The pH value is adjusted by adding lime to make it more suitable for hydration reaction. The ammonium chloride hydration promoter is used to further promote the hydration reaction. When recycling, the ammonium sulfate produced in the reaction process is also a hydration promoter, which makes the residual unhydrated gypsum hydrated and participate in the reaction. The by-products produced in the production process are fully utilized to modify the fluorinated gypsum, accelerate the hydration process of the fluorinated gypsum, and improve the conversion efficiency of the fluorinated gypsum, thereby further improving the conversion efficiency of the fluorinated gypsum recovery. The problem of low conversion efficiency when recovering fluorinated gypsum in the prior art is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of a method for recovering fluorinated gypsum according to an embodiment of the present invention;

[0025] Figure 2 The present invention is a process flow chart of a fluorinated gypsum recovery method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] In addition, the term "and / or" as used herein includes any and all combinations of one or more related listed items. In the detailed description and claims, a list of items connected by the term "one of" may mean any of the listed items. For example, if items A and B are listed, the phrase "one of A and B" means only A or only B. In another example, if items A, B, and C are listed, the phrase "one of A, B, and C" means only A; only B; or only C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements. In the detailed description and claims, a list of items connected by the terms "at least one of", "at least one of" or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, the phrase "at least one of A and B" or "at least one of A or B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, the phrase "at least one of A, B, and C" or "at least one of A, B, or C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0028] The present invention aims to solve the problem that the current recycling of fluorinated gypsum mainly adopts the low efficiency of long-term stacking and natural hydration, and proposes a method for recycling fluorinated gypsum, wherein, Figure 1 The fluorine gypsum recovery method includes steps S10 to S14.

[0029] Step S10, mixing fluorinated gypsum and lime in a set ratio, and then grinding them in a ball mill to obtain gypsum powder with a preset particle size.

[0030] Among them, the mixture of fluorgypsum and lime is ground in a ball mill to obtain a powder with a particle size of less than 100-150 mesh. Specifically, after grinding in the ball mill, the particle size of the gypsum powder becomes very fine, increasing its specific surface area. This change enables the gypsum powder to react more quickly and fully when in contact with the ammonium chloride solution. In addition, lime is used to neutralize the fluorgypsum and adjust the pH value to a preset range, such as 7.5-8.5. In addition, because the residual sulfuric acid content of each batch of fluorgypsum discharged from the production line is not necessarily the same, the amount of lime used to neutralize the sulfuric acid is not fixed. Therefore, the ratio of fluorgypsum to lime is not a fixed value, but the amount of lime is adjusted according to the pH value after mixing.

[0031] Step S11, mixing the gypsum powder and the ammonium chloride solution in a preset ratio and stirring to obtain a mixed solution, and filtering the mixed solution to obtain a filter cake.

[0032] Specifically, a 5-10% ammonium chloride solution is prepared, and the gypsum powder and the ammonium chloride solution are mixed in a mass ratio of 1:3-5, and the stirring speed is 60-120 r / min for 3-6 hours. By stirring at a stirring speed of 60-120 r / min for 3-6 hours, the gypsum powder and the ammonium chloride solution can be fully mixed, ensuring that the ammonium chloride in the solution can contact each gypsum particle, and the reaction is more uniform and sufficient.

[0033] The mixed liquid is filtered to obtain filter cake and filtrate respectively, and the filtrate can be returned for reuse.

[0034] Step S12, placing the obtained filter cake in an ammonia solution and stirring it, adding a carbon source under stirring, adjusting the sulfur-carbon ratio and ammonia-carbon ratio in the mixed solution to preset ratios and reacting for a preset time.

[0035] The filter cake is placed in a 15-25% ammonia solution and stirred evenly, and ammonium carbonate (NH4HCO3) is added or carbon dioxide (CO2) is introduced under stirring to adjust the sulfur-carbon ratio to 1.05-1.2 and the ammonia-carbon ratio to 2.0-2.2, and react for 1-1.5 hours.

[0036] Step S13, filtering after the reaction is completed, collecting the filtrate, and sequentially performing evaporation concentration, cooling crystallization, and centrifugal separation to obtain the finished ammonium sulfate crystals.

[0037] After the reaction is completed, the post-reaction solution can be filtered to obtain new filtrate and filter cake, the filter cake can be returned for neutralization with fluorgypsum, the pH value can be adjusted, the filtrate is concentrated, and after removing a portion of the water, it is cooled and crystallized and centrifuged to obtain a finished ammonium sulfate crystal, wherein ammonia can be recovered from the tail gas after evaporation and concentration.

[0038] Step S14, adding potassium chloride solid to the remaining filtrate, performing a preset reaction, cooling to room temperature for crystallization, and centrifuging to obtain a finished potassium sulfate crystal.

[0039] In which, potassium chloride solid is added to the mother liquor after the ammonium sulfate crystal product is recovered in the above step, with a nitrogen-potassium ratio of 1 to 1.10, and the temperature is raised to 85 to 95° C. under stirring, and the reaction is kept warm for 1 to 1.5 hours. After the reaction is completed, it is cooled to room temperature for crystallization, and centrifuged to obtain a potassium sulfate crystal product.

[0040] In addition, the mother liquor after the potassium sulfate crystal product is recovered in the above step can be evaporated and concentrated, cooled and crystallized, and then centrifuged to obtain ammonium chloride solid. The mother liquor is recycled and evaporated, and the ammonium chloride solid can be used to return and react with fluorgypsum.

[0041] For further information, see Figure 2 The embodiment of the present invention adopts a recycling method to comprehensively utilize fluorinated gypsum, and uses fluorinated gypsum to prepare potassium sulfate and co-produce ammonium sulfate. The ammonium sulfate produced in the reaction process is a hydration promoter, which makes the residual unhydrated gypsum hydrated and participate in the reaction. The by-products produced in the production process are fully utilized to modify the fluorinated gypsum, accelerate the hydration process of the fluorinated gypsum, and improve the conversion rate of the fluorinated gypsum.

[0042] In addition, in some optional embodiments of the present invention, after the step of mixing fluorgypsum and lime in a set ratio and then grinding in a ball mill to obtain gypsum powder with a preset particle size, the step further includes:

[0043] The gypsum powder is cleaned to remove surface impurities, and then the gypsum powder is plasma treated to improve the surface activity of the gypsum powder.

[0044] The gypsum powder is cleaned to remove impurities on the surface, ensuring that the surface of the gypsum powder is clean and laying a foundation for subsequent plasma treatment. Specifically, the cleaning step may include:

[0045] Initial cleaning: Rinse the gypsum powder with water to remove loose particles and soluble impurities on the surface.

[0046] Ultrasonic cleaning: finally put the gypsum powder into an ultrasonic cleaner, add an appropriate amount of deionized water or diluted detergent solution, and perform ultrasonic cleaning to further remove surface impurities.

[0047] Rinsing: The gypsum powder is then rinsed with copious amounts of deionized water to remove any residual detergent or other chemicals.

[0048] Drying: Finally, the gypsum powder is dried in a drying oven to ensure that there is no residual moisture on its surface. In addition, in some optional embodiments of the present invention, the pH value of the gypsum powder can be adjusted according to actual conditions after washing.

[0049] Furthermore, a plasma treatment device is used to put the cleaned gypsum powder into a treatment chamber of the plasma treatment device, and the gypsum powder is subjected to plasma treatment, thereby changing its surface structure and improving its surface activity.

[0050] Furthermore, after the surface active treatment, nitrogen is introduced into the process of the hydration reaction of the gypsum powder and the ammonium chloride solution, wherein, during the hydration reaction, nitrogen can provide an inert atmosphere to prevent other gases (such as oxygen) from interfering with the reaction, which helps to improve the purity of the reaction. On the other hand, lime is added to adjust the pH value of the fluorgypsum so that the pH value environment is more suitable for the occurrence of the hydration reaction. Specifically, the pH value is adjusted to 7.5-8.5. In addition, by introducing nitrogen, under nitrogen conditions, the carbonation reaction can be suppressed and the pH value can be kept relatively stable, which helps to maintain the normal progress of the hydration reaction and further improve the purity of the hydration reaction. In addition, the temperature of the hydration reaction can also be controlled by controlling the temperature of the nitrogen, so that the generation of the hydration reaction can be more conducive.

[0051] In summary, the fluorinated gypsum recovery method proposed in the above embodiment of the present invention is as follows: fluorinated gypsum and lime are mixed in a set ratio, and then ground in a ball mill to obtain gypsum powder of a preset particle size; the gypsum powder and ammonium chloride solution are mixed and stirred in a preset ratio to obtain a mixed solution, and the mixed solution is filtered to obtain a filter cake; the obtained filter cake is placed in an ammonia solution and stirred, a carbon source is added under stirring, the sulfur-carbon ratio and ammonia-carbon ratio in the mixed solution are adjusted to preset ratios, and then reacted for a preset time; after the reaction is completed, the solution is filtered, and the filtrate is collected and evaporated and concentrated, cooled and crystallized, and centrifuged to obtain a finished ammonium sulfate crystal product; Potassium chloride solid is added to the remaining filtrate, and after a preset reaction, it is cooled to room temperature for crystallization and centrifugal separation to obtain a finished potassium sulfate crystal product. The pH value is adjusted by adding lime to make it more suitable for hydration reaction. Ammonium chloride hydration promoter is used to further promote the hydration reaction. When recycling, the ammonium sulfate produced in the reaction process is also a hydration promoter, which makes the residual unhydrated gypsum hydrated and participates in the reaction. The by-products produced in the production process are fully utilized to modify the fluorinated gypsum, accelerate the hydration process of the fluorinated gypsum, and improve the conversion efficiency of the fluorinated gypsum, thereby further improving the conversion efficiency of the fluorinated gypsum recovery. The problem of low conversion efficiency when recovering fluorinated gypsum in the prior art is solved.

[0052] In order to facilitate understanding of the present invention, several embodiments of the present invention are provided below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0053] Example 1

[0054] This embodiment provides a fluorinated gypsum recovery method for recovering ammonium sulfate, the method comprising:

[0055] Mix fluorinated gypsum and lime in a set ratio, and then grind them in a ball mill to obtain 120-mesh gypsum powder;

[0056] The gypsum powder and 10% ammonium chloride solution are mixed and stirred at a ratio of 1:4 to obtain a mixed solution, and the mixed solution is filtered to obtain a filter cake;

[0057] The obtained filter cake was placed in a 20% ammonia solution and stirred at a speed of 80 r / min for 5 h. Ammonium carbonate was added under stirring to adjust the sulfur-carbon ratio to 1.05 and the ammonia-carbon ratio to 2.2 in the mixed solution and reacted for 1 h.

[0058] After the reaction is completed, the reaction is filtered, and the filtrate is collected and evaporated, concentrated, cooled, crystallized, and centrifuged to obtain the finished ammonium sulfate crystals.

[0059] Example 2

[0060] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 1 is that:

[0061] The reaction time after adding the ammonia solution and the carbon source was 1.5.

[0062] Example 3

[0063] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 1 is that:

[0064] Sulfur-carbon ratio is 1.1

[0065] Example 4

[0066] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 1 is that:

[0067] Sulfur-carbon ratio is 1.2

[0068] Example 5

[0069] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 1 is that:

[0070] Ammonia to carbon ratio: 2.03

[0071] Example 6

[0072] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 1 is that:

[0073] Ammonia to carbon ratio 2.1

[0074] Example 7

[0075] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 1 is that:

[0076] Ammonia to carbon ratio: 2.16

[0077] Example 8

[0078] This embodiment provides a fluorinated gypsum recovery method for recovering potassium sulfate, the method comprising:

[0079] Mix fluorinated gypsum and lime in a set ratio, and then grind them in a ball mill to obtain 120-mesh gypsum powder;

[0080] The gypsum powder and 10% ammonium chloride solution are mixed and stirred at a ratio of 1:4 to obtain a mixed solution, and the mixed solution is filtered to obtain a filter cake;

[0081] The obtained filter cake was placed in a 20% ammonia solution and stirred at a speed of 80 r / min for 5 h. Ammonium carbonate was added under stirring to adjust the sulfur-carbon ratio to 1.05 and the ammonia-carbon ratio to 2.2 in the mixed solution and reacted for 1 h.

[0082] After the reaction is completed, the reaction is filtered, and the filtrate is collected and evaporated, concentrated, cooled, crystallized, and centrifuged to obtain the finished ammonium sulfate crystals;

[0083] Solid potassium chloride was added to the remaining filtrate, the nitrogen-potassium ratio was maintained at 1.05, the temperature was raised to 95° C. under stirring, the reaction was kept warm for 1.5 h, and the potassium sulfate crystals were obtained by centrifugation.

[0084] Example 9

[0085] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 8 is that:

[0086] Raise the temperature to 95°C.

[0087] Example 10

[0088] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 8 is that:

[0089] 85℃.

[0090] Embodiment 11

[0091] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 8 is that:

[0092] Keep the reaction warm for 1h.

[0093] Example 12

[0094] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 8 is that:

[0095] Keep the reaction warm for 2h.

[0096] Example 13

[0097] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 8 is that:

[0098] Maintain a nitrogen to potassium ratio of 1.

[0099] Example 13

[0100] This embodiment also proposes a method for recovering fluorinated gypsum. The difference between the method for recovering fluorinated gypsum proposed in this embodiment and the method for recovering fluorinated gypsum proposed in Example 8 is that:

[0101] Maintain a nitrogen to potassium ratio of 1.1.

[0102] Please refer to Table 1 and Table 2 below, which respectively show the parameters corresponding to the above-mentioned embodiments 1-7 and 8 to 14 of the present invention, as shown in the following table:

[0103] Table 1

[0104]

[0105] Table 2

[0106]

[0107] In practical applications, various recovery data obtained by using the parameters of the above-mentioned embodiments 1-7 of the present invention and various recovery data obtained by using the parameters of embodiments 8 to 14 are respectively recovered. It should be noted that, in order to ensure the accuracy of the experimental results, the above-mentioned embodiments are the same except for the above-mentioned parameters. The data are shown in Table 3 below:

[0108] Table 3

[0109]

[0110] In summary, combined with the data in Tables 1 and 2 above, it can be clearly seen that the present invention prepares ammonium sulfate, and the calcium sulfate conversion rate reaches more than 97%, and the ammonium sulfate content is more than 99%, which meets the national standard first-class product requirements. The present invention prepares potassium sulfate, and the ammonium sulfate conversion rate reaches more than 94%, and the potassium content is more than 50%, which meets the national standard first-class product requirements. The gypsum powder of a preset particle size is obtained by mixing fluorgypsum and lime in a set ratio, and then grinding in a ball mill; the gypsum powder and ammonium chloride solution are mixed and stirred in a preset ratio to obtain a mixed solution, and the mixed solution is filtered to obtain a filter cake; the obtained filter cake is placed in an ammonia solution and stirred, and a carbon source is added under stirring, and the sulfur-carbon ratio and ammonia-carbon ratio in the mixed solution are adjusted to the preset ratios and reacted for a preset time; after the reaction is completed, it is filtered, and the filtrate is collected and evaporated and concentrated, cooled and crystallized, and centrifuged in turn to obtain the finished ammonium sulfate crystals; potassium chloride solid is added to the remaining filtrate After the preset reaction, the product of potassium sulfate crystal is obtained by cooling to room temperature crystallization and centrifugal separation. The pH value is adjusted by adding lime to make it more suitable for hydration reaction. The ammonium chloride hydration promoter is used to further promote the hydration reaction. When recycling, the ammonium sulfate produced in the reaction process is also a hydration promoter, which makes the residual unhydrated gypsum hydrated and participates in the reaction. The by-products produced in the production process are fully utilized to modify the fluorinated gypsum, accelerate the hydration process of the fluorinated gypsum, and improve the conversion efficiency of the fluorinated gypsum, thereby further improving the conversion efficiency of the fluorinated gypsum recovery. The problem of low conversion efficiency in the recovery of fluorinated gypsum in the prior art is solved.

[0111] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for recovering fluorinated gypsum, It is characterized in that The method comprises: Mixing fluorinated gypsum and lime in a set ratio, and then grinding them in a ball mill to obtain gypsum powder with a preset particle size; The gypsum powder and the ammonium chloride solution are mixed and stirred in a preset ratio to obtain a mixed solution, and the mixed solution is filtered to obtain a filter cake; The obtained filter cake is placed in an ammonia solution and stirred, a carbon source is added under stirring, and the sulfur-carbon ratio and ammonia-carbon ratio in the mixed solution are adjusted to preset ratios and reacted for a preset time; After the reaction is completed, the reaction is filtered, and the filtrate is collected and evaporated, concentrated, cooled, crystallized, and centrifuged to obtain the finished ammonium sulfate crystals; Potassium chloride solid is added to the remaining filtrate, and after a preset reaction, it is cooled to room temperature for crystallization and centrifuged to obtain a finished potassium sulfate crystal product.

2. The method for recovering fluorinated gypsum according to claim 1, It is characterized in that The particle size of the gypsum powder is less than 100-150 meshes.

3. The method for recovering fluorinated gypsum according to claim 1, It is characterized in that The mass fraction of the ammonium chloride solution is 5-10%, and the gypsum powder and the ammonium chloride solution are mixed in a mass ratio of 1:3-5.

4. The method for recovering fluorinated gypsum according to claim 1, It is characterized in that The stirring speed of the gypsum powder and the ammonium chloride solution is 60-120 r / min, and the stirring time is 3-6 hours.

5. The method for recovering fluorgypsum according to claim 1, It is characterized in that Carbon sources include ammonium carbonate or carbon dioxide.

6. The method for recovering fluorinated gypsum according to claim 5, It is characterized in that The sulfur-carbon ratio is 1.05-1.2, the ammonia-carbon ratio is 2.0-2.2, and the reaction time is 1-1.5h.

7. The method for recovering fluorgypsum according to claim 1, It is characterized in that In the step of adding potassium chloride solid to the filtrate, performing a preset reaction, cooling to room temperature for crystallization, and centrifuging to obtain a finished potassium sulfate crystal product, the nitrogen-potassium ratio is 1 to 1.

10.

8. The method for recovering fluorgypsum according to claim 1, It is characterized in that The preset reaction is to heat to 85-95°C under stirring and keep the temperature for 1-1.5 hours.

9. The method for recovering fluorinated gypsum according to claim 1, It is characterized in that The step of collecting the filtrate and sequentially performing evaporation concentration, cooling crystallization and centrifugal separation to obtain the finished ammonium sulfate crystals also includes: The filter cake is collected and used for neutralization with the fluorgypsum.

10. The method for recovering fluorinated gypsum according to claim 1, It is characterized in that The step of adding potassium chloride solid to the remaining filtrate, performing a preset reaction, cooling to room temperature for crystallization, and centrifuging to obtain a finished potassium sulfate crystal also includes: The filtrate from which the potassium sulfate crystal product is recovered is evaporated and concentrated, cooled and crystallized, and then centrifuged to obtain ammonium chloride solid for mixing with the gypsum powder.

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